For a "vertical riser" saving weight is key but you are still quite a bit above my rocket which weighed just 695 g ready to go. It had about 850g static thrust available.
The development and build is described here and was, to put it mildly, rather long and complex. The initial concept proved to be unworkable so had to be revised and then a new bigger version built. In all it took 7 months work before the first vertical take off took place.
Yes it worked but most definitely not a simple build. The fact that it was a true scale model did not make much if any difference to the way it performed and having proper wings did at least get over the problem of landing.